1. Field of the Invention
This invention relates to a new and improved, single limb breathing circuit assembly for use in circle absorber anesthetic systems, and to a new and improved absorber which is particularly, though not exclusively, adapted for use therewith.
2. Description of the Prior Art
The circle absorber anesthetic systems of the prior art will generally be seen to comprise relatively bulky and heavy double limb breathing circuit assemblies which function to supply relatively cool and dry oxygen and anesthetic mixtures to the patient. Among the more significant disadvantages of these double limb breathing circuit assemblies are the overall unwieldiness and tendency of the same to become entangled and/or simply get in the way during the course of an operation, and/or to become disconnected from the patient. In addition, and particularly in the course of surgery of long duration, the relatively cool and dry gases supplied thereby have a clearly demonstrated physiologically adverse drying effect on the ciliated epithelium of the tracheobronchial tree of the patient, and can be conductive to patient hypothermia.
The single limb breathing circuit assemblies of the prior art are generally of the open circuit type which do not separate inhaled and exhaled gases and which suffer from a wide range of significant disadvantages. More specifically, these disadvantages of the single limb breathing circuit assemblies of the prior art include: the necessity for relatively high anesthetic and oxygen inflows to purge carbon dioxide with resultant relatively high anesthetic costs per operation; relatively high levels of re-breathing of carbon dioxide despite all efforts to purge the same with resultant physiologically adverse increase in the secretion of adrenalin by the patient; the supply of relatively dry and cool oxygen and anesthetic mixtures at relatively high flow rates to the patient with resultant physiologically adverse effects on the patient as discussed hereinabove; the anesthetic pollution of the operating room due to the direct venting of the excess anesthetic thereinto with resultant substantial increase in the exposure of operating room personnel to a variety of documented personal risks and, in the case of pregnant female personnel, to the additional risks of spontaneous abortion or serious malformation of the unborn child; the need for special single outlet adaptor means to enable the circuit to function with conventional and very widely used anesthetic supply equipment; the inability of the circuit to provide for patient hyperventilation with resultant lack of utility thereof for use in certain neurosurgical procedures wherein shrinkage of the brain is required and air embolism must be prevented; the inability to provide for spontaneous patient ventilation in the absence of even higher anesthetic and oxygen inflows with resultant even higher levels of anesthetic pollution of the operating room; and the necessity for the use of cumbersome and not always fully reliable nomograms for estimation of anesthetic and oxygen inflows to insure safe ventilation in instances wherein the patient is feverish and/or in a high metabolic state, or a state in which carbon dioxide production by the body is high.
In addition, the absorbers of the prior art will generally be found to be relatively bulky, complex, and expensive and, in many instances, incapable of delivering gases for inspiration by the patient to the breathing circuit at very desirable high temperature and humidity levels. Also, no prior art absorbers are known which include provision for the precise proportioning of the fresh gas inflow from the anesthetic machine between the absorber inlet and outlet to in turn enable precise control in the temperature and humidity of the gases as delivered from the absorber to the inspiratory passage of the breathing circuit for inspiration by the patient.